One downside of going passive... if someone ever decided to upgrade their driver to say, a TAD.... then the passive is going to need some reconfiguring ($$$ but I don't know how much). An active allows you to reprogram & be done in minutes.
Ya'll don't forget....he's already got a pair of LaScalas. He can jump to a (potential) end goal (Full Jubilee's) or he can take steps along the way (JubeScala)
He can get an active (though I think a passive exists for the K69 driver?) and put/place/slap the K402 on top of his LaScala bin. That will cost him what?? something like... let's (guess) and say $2,500'ish. Add another $1,500 (guessing) for a good active and he might find himself done. He already loves the sound of his LaScalas. I think those of us who've heard the 402 know what kind of step up it will give him.
Heck Schu... keep in mind the 402 alone is larger in height/width than the entire LaScala speaker.
I'm all for someone jumping into (what I feel would be) their end game.... Schu strikes me as more reserved than that so the JubeScala would be a way for him to improve his top end while knowing later on, he'd always have an option of improving his bottom end (swap LaScala for Jube bass bin)
Schu.... if you ever decide to go active, know that I went from passive to active overnight, made my own wires (and will admit to cross/wiring a couple of them). I did this with ZERO experience doing these things and other than the crossed wires, was successful first time out.
It's not as complex as it sounds....it's really a matter of gathering the correct ingredients and putting them together. You don't have to create anything if you don't want to. Just plug/program and play.
Side note: I'd take the K402 with standard Klipsch driver (K69 in my case, I forget current drivers number) against the rest of their lineup. In other words, the TAD driver, great as it is, is just the icing on the cake. You are already making a significant improvement with the stock horn/driver alone, the TAD isn't 'required' to get a huge improvement in sound.
The direct radiating makes it possible to use passive. You don't have the time alignment issues to deal with. Fully hornloaded LF creates the time alignment issues and makes the passive options much more limited, and very expensive.
@Deang can build you a set.of passives but I think he will tell you that would he in the thousands.
It isn't that complex, we can get you the settings. If I can do it, anyone can (seriously).